Trigonocephaly is a congenital condition of premature fusion of the

metopic suture The frontal suture is a fibrous connective tissue, fibrous suture (joint), joint that divides the two halves of the frontal bone of the human skull, skull in infants and children. Typically, it completely fuses between three and nine months of ag ...

(from the Greek , "forehead"), leading to a triangular forehead. The merging of the two frontal bones leads to transverse growth restriction and parallel growth expansion. It may occur syndromic, involving other abnormalities, or isolated. The term is from the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

, "triangle", and , "head".

Cause

Trigonocephaly can either occur syndromatic or isolated. Trigonocephaly is associated with the following syndromes:

Opitz syndrome Trigonocephaly is a congenital condition of premature fusion of the metopic suture (from the Greek , "forehead"), leading to a triangular forehead. The merging of the two frontal bones leads to transverse growth restriction and parallel growth ex ...

Muenke syndrome Muenke syndrome, also known as FGFR3-related craniosynostosis, is a human specific condition characterized by the premature closure of certain bones of the skull during development, which affects the shape of the head and face. First described by M ...

Jacobsen syndrome Jacobsen syndrome is a rare chromosomal disorder resulting from deletion of genes from chromosome 11 that includes band 11q24.1. It is a congenital disorder. Since the deletion takes place on the q arm of chromosome 11, it is also called 11q te ...

Baller–Gerold syndrome Baller–Gerold syndrome (BGS) is a rare genetic syndrome that involves premature fusion of the skull bones and malformations of facial, forearm and hand bones. The symptoms of Baller–Gerold syndrome overlap with features of a few other genetics ...

and

Say–Meyer syndrome Say–Meyer syndrome is a rare X-linked genetic disorder that is mostly characterized as developmental delay. It is one of the rare causes of short stature. It is closely related with trigonocephaly (a misshapen forehead due to premature fusion ...

. The etiology of trigonocephaly is mostly unknown although there are three main theories. Trigonocephaly is probably a multifactorial congenital condition, but due to limited proof of these theories this cannot safely be concluded.

Intrinsic bone malformation

The first theory assumes that the origin of pathological synostosis lies within disturbed bone formation early on in the pregnancy. Causes can either be genetic (9p22–24, 11q23, 22q11,

FGFR1 Fibroblast growth factor receptor 1 (FGFR1), also known as basic fibroblast growth factor receptor 1, fms-related tyrosine kinase-2 / Pfeiffer syndrome, and CD331, is a receptor tyrosine kinase whose ligands are specific members of the fibroblast ...

mutation), metabolic ( TSH suppletion in

hypothyroidism Hypothyroidism (also called ''underactive thyroid'', ''low thyroid'' or ''hypothyreosis'') is a disorder of the endocrine system in which the thyroid gland does not produce enough thyroid hormone. It can cause a number of symptoms, such as po ...

) or pharmaceutical (

valproate Valproate (VPA) and its valproic acid, sodium valproate, and valproate semisodium forms are medications primarily used to treat epilepsy and bipolar disorder and prevent migraine headaches. They are useful for the prevention of seizures in those ...

epilepsy Epilepsy is a group of non-communicable neurological disorders characterized by recurrent epileptic seizures. Epileptic seizures can vary from brief and nearly undetectable periods to long periods of vigorous shaking due to abnormal electrical ...

Fetal-head constraint

The second theory says that synostosis begins when the fetal head gets hindered in the

pelvic outlet The lower circumference of the lesser pelvis is very irregular; the space enclosed by it is named the inferior aperture or pelvic outlet. It is an important component of pelvimetry. Boundaries It has the following boundaries: * anteriorly: the pub ...

during birth.

Intrinsic brain malformation

The third theory predominates disturbed brain formation of the two

frontal lobes The frontal lobe is the largest of the four major lobes of the brain in mammals, and is located at the front of each cerebral hemisphere (in front of the parietal lobe and the temporal lobe). It is parted from the parietal lobe by a groove betwe ...

as the main issue behind synostosis. Limited growth of the frontal lobes leads to an absence of stimuli for cranial growth, therefore causing premature fusion of the metopic suture.

Diagnosis

Diagnosis can be characterized by typical facial and cranial deformities. Observatory signs of trigonocephaly are: * a triangular forehead seen from top view leading to a smaller

anterior cranial fossa The anterior cranial fossa is a depression in the floor of the cranial base which houses the projecting frontal lobes of the brain. It is formed by the orbital part of frontal bone, orbital plates of the Frontal bone, frontal, the cribriform plate ...

* a visible and palpable midline ridge *

hypotelorism Hypotelorism is an abnormally decreased distance between two organs or bodily parts, usually pertaining to the eye sockets (orbits), also known as orbital hypotelorism. Causes It is often a result of fetal alcohol syndrome (FAS), caused by lar ...

inducing ethmoidal

hypoplasia Hypoplasia (from Ancient Greek ὑπo- ''hypo-'' 'under' + πλάσις ''plasis'' 'formation'; adjective form ''hypoplastic'') is underdevelopment or incomplete development of a tissue or organ.3D-CT,

Röntgenography Radiology ( ) is the medical discipline that uses medical imaging to diagnose diseases and guide their treatment, within the bodies of humans and other animals. It began with radiography (which is why its name has a root referring to radiatio ...

MRI Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio waves ...

) show: *

epicanthal folds An epicanthic fold or epicanthus is a skin fold of the upper eyelid that covers the inner corner (medial canthus) of the eye. However, variation occurs in the nature of this feature and the possession of "partial epicanthic folds" or "slight ...

in limited cases * teardrop-shaped orbits angulated towards the midline of the forehead ('surprised coon' sign) in severe cases * a contrast difference between a röntgenograph of a normal and a trigonocephalic skull * anterior curving of the metopic suture seen from

lateral Lateral is a geometric term of location which may refer to: Healthcare *Lateral (anatomy), an anatomical direction *Lateral cricoarytenoid muscle *Lateral release (surgery), a surgical procedure on the side of a kneecap Phonetics *Lateral cons ...

view of the cranium on a röntgenograph * a normal cephalic index (maximum

cranium The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, the ...

width / maximum cranium length) however, there is bitemporal shortening and biparietal broadening The neuropsychological development is not always affected. These effects are only visible in a small percentage of children with trigonocephaly or other suture synostoses. Neuropsychological signs are: * problems in behaviour, speech and language * mental retardation * neurodevelopmental delays such as

attention deficit hyperactivity disorder Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterised by excessive amounts of inattention, hyperactivity, and impulsivity that are pervasive, impairing in multiple contexts, and otherwise age-inap ...

(ADHD),

oppositional defiant disorder Oppositional defiant disorder (ODD) is listed in the DSM-5 under ''Disruptive, impulse-control, and conduct disorders'' and defined as "a pattern of angry/irritable mood, argumentative/defiant behavior, or vindictiveness". This behavior is us ...

(ODD),

autism spectrum disorder The autism spectrum, often referred to as just autism or in the context of a professional diagnosis autism spectrum disorder (ASD) or autism spectrum condition (ASC), is a neurodevelopmental disorder, neurodevelopmental condition (or conditions) ...

(ASD), and

conduct disorder Conduct disorder (CD) is a mental disorder diagnosed in childhood or adolescence that presents itself through a repetitive and persistent pattern of behavior that includes theft, lies, physical violence that may lead to destruction, and reckles ...

(CD). Many of these delays become evident at school age.

Treatment

Treatment is surgical with attention to form and volume. Surgery usually takes place before the age of one since it has been reported that the intellectual outcome is better.

Fronto-supraorbital advancement and remodelling

A form of surgery is the so-called fronto-supraorbital advancement and remodelling. Firstly, the supraorbital bar is remodelled by a wired

greenstick fracture A greenstick fracture is a fracture in a young, soft bone in which the bone bends and breaks. Greenstick fractures occur most often during infancy and childhood when bones are soft. The name is by analogy with green (i.e., fresh) wood which simil ...

to straighten it. Secondly, the supraorbital bar is moved 2 cm. forward and fixed only to the frontal process of the

zygoma The term zygoma generally refers to the zygomatic bone, a bone of the human skull commonly referred to as the cheekbone or malar bone, but it may also refer to: * The zygomatic arch, a structure in the human skull formed primarily by parts of the z ...

without fixation to the cranium. Lastly, the frontal bone is divided into two, rotated and attached to the supraorbital bar causing a nude area (

craniectomy Decompressive craniectomy ('' crani-'' + '' -ectomy'') is a neurosurgical procedure in which part of the skull is removed to allow a swelling brain room to expand without being squeezed. It is performed on victims of traumatic brain injury, st ...

) between the

parietal bone The parietal bones () are two bones in the Human skull, skull which, when joined at a fibrous joint, form the sides and roof of the Human skull, cranium. In humans, each bone is roughly quadrilateral in form, and has two surfaces, four borders, an ...

and

frontal bone The frontal bone is a bone in the human skull. The bone consists of two portions.''Gray's Anatomy'' (1918) These are the vertically oriented squamous part, and the horizontally oriented orbital part, making up the bony part of the forehead, par ...

. Bone will eventually regenerate since the

dura mater In neuroanatomy, dura mater is a thick membrane made of dense irregular connective tissue that surrounds the brain and spinal cord. It is the outermost of the three layers of membrane called the meninges that protect the central nervous system. ...

lies underneath (the dura mater has osteogenic capabilities). This results in an advancement and straightening of the forehead.

'Floating forehead technique'

The so-called 'floating forehead technique' combined with the remodelling of the supraorbital bar is derived from the fronto-supraorbital advancement and remodelling. The supraorbital bar is remodelled as described above. The frontal bone is split in two pieces. Instead of using both pieces as in fronto-supraorbital advancement and remodelling, only one piece is rotated and attached to the supraorbital bar. This technique also leaves a craniectomy behind.

Other

* Suturectomy *

Distraction osteogenesis Distraction osteogenesis (DO), also called callus distraction, callotasis and osteodistraction, is a process used in orthopedic surgery, podiatric surgery, and oral and maxillofacial surgery to repair skeletal deformities and in reconstructive s ...

* Minimal invasive endoscopic surgery These approaches are 2D solutions for a 3D problem, therefore the results are not optimal. Distraction osteogenesis and minimal invasive endoscopic surgery are yet in experimental phase.

Outcomes

Surgical

Trigonocephaly seems to be the most compliant form of

craniosynostosis Craniosynostosis is a condition in which one or more of the fibrous sutures in a young infant's skull prematurely fuses by turning into bone (ossification), thereby changing the growth pattern of the skull. Because the skull cannot expand perpe ...

for surgery. Because of standardization of current surgical approaches there is no surgical mortality and complications are few to none. The simple suturectomy is presently insufficient to adjust the complicated growth restrictions caused by metopic synostosis. On the other hand, the fronto-supraorbital advancement and remodelling and the 'floating forehead technique' create sufficient space for brain growth and result in a normal horizontal axis of the orbits and supraorbital bar. The fronto-supraorbital advancement and remodelling is the most used method nowadays. Over the past few years distraction osteogenesis has been gradually acknowledged since it has a positive effect on hypotelorism. Expanding the distance between the orbits using springs seems to be successful. However, there are discussions whether hypotelorism really needs to be corrected. The minimal invasive endoscopic surgery has been gaining attention since the early '90s, however, it has technical limitations (only strip craniectomy is possible). Attempts have been made to reach beyond these limits.

Aesthetic

Aesthetic Aesthetics, or esthetics, is a branch of philosophy that deals with the nature of beauty and taste, as well as the philosophy of art (its own area of philosophy that comes out of aesthetics). It examines aesthetic values, often expressed th ...

outcome of metopic

synostosis Synostosis (plural: synostoses) is fusion of two or more bones. It can be normal in puberty, fusion of the epiphyseal plate to become the epiphyseal line, or abnormal. When synostosis is abnormal it is a type of dysostosis. Examples of synostoses ...

surgery Surgery ''cheirourgikē'' (composed of χείρ, "hand", and ἔργον, "work"), via la, chirurgiae, meaning "hand work". is a medical specialty that uses operative manual and instrumental techniques on a person to investigate or treat a pat ...

is persistently good with reoperation hazards below 20%. In 1981 Anderson advised ''that craniofacial operations for synostosis should be as extensive as necessary'' after a study of 107 cases of metopic and coronal synostosis. Surgery does not provide a 100% natural outcome, mostly there will be minor irregularities. Reoperations are usually performed on more severe cases (including syndromic metopic synostosis). The

and temporal hollowing are the most difficult to correct: the hypotelorism usually remains under corrected and a second operation is often needed for correction of temporal hollowing.

Neurological

The highest rate of neurological problems of single suture synostosis are seen in patients with trigonocephaly. Surgery is performed generally before the age of one because of claims of better intellectual outcome. Seemingly surgery does not influence the high incidence of neurodevelopment problems in patients with metopic synostosis. Neurological disorders such as ADHD, ASD, ODD and CD are seen in patients with trigonocephaly. These disorders are usually also associated with decreased IQ. The presence of ADHD, ASD and ODD is higher in cases with an IQ below 85. This is not the case with CD which showed an insignificant increase at an IQ below 85.

Epidemiology

The incidence of metopic synostosis is roughly between 1:700 and 1:15,000 newborns globally (differs per country). Trigonocephaly is seen more in males than females ranging from 2:1 to 6.5:1. Hereditary relations in metopic synostosis have been found of which 5.5% were well defined syndromic. Maternal age and a birth weight of less than 2500g may also play a role in trigonocephaly. These data are based on estimations and do not give factual information. Only one article gives valuable and reliable information regarding the incidence of metopic synostosis in the Netherlands. The incidence in the Netherlands showed an increase from 0.6 (1997) to 1.9 (2007) for every 10,000 live births.

History

In former times people born with malformed skulls were rejected based upon their appearance.Strickler M, van der Meulen J, Rahael B, Mazolla R. Craniofacial malformations. Edinburgh, London, Melbourne, New York: Churchill Livingston, 1990. This still persists today in various parts of the world even though the intellectual development is often normal. The Austrian physician

Franz Joseph Gall Franz Josef Gall (; 9 March 175822 August 1828) was a German neuroanatomist, physiologist, and pioneer in the study of the localization of mental functions in the brain. Claimed as the founder of the pseudoscience of phrenology, Gall was an earl ...

presented the science of

phrenology Phrenology () is a pseudoscience which involves the measurement of bumps on the skull to predict mental traits.Wihe, J. V. (2002). "Science and Pseudoscience: A Primer in Critical Thinking." In ''Encyclopedia of Pseudoscience'', pp. 195–203. C ...

in the early 19th century through his work ''The Anatomy and Physiology of the Nervous System in General, and of the Brain in Particular''.Phrenology. http://www.phrenology.org/

Hippocrates Hippocrates of Kos (; grc-gre, Ἱπποκράτης ὁ Κῷος, Hippokrátēs ho Kôios; ), also known as Hippocrates II, was a Greek physician of the classical period who is considered one of the most outstanding figures in the history of ...

described trigonocephaly as follows: ''Men's heads are by no means all like to one another, nor are the sutures of the head of all men constructed in the same form. Thus, whoever has a prominence in the anterior part of the head (by prominence is meant the round protuberant part of the bone which projects beyond the rest of it), in him the sutures of the head take the form of the Greek letter 'tau', τ''.

Hermann Welcker Hermann Welcker (8 April 1822 – 12 September 1897) was a German anatomist and anthropologist who was born in Giessen. He was a nephew to philologist Friedrich Gottlieb Welcker (1784–1868). In 1851 he earned his doctorate from the University ...

coined the term trigonocephaly in 1862. He described a child with a V-shaped skull and a

cleft lip A cleft lip contains an opening in the upper lip that may extend into the nose. The opening may be on one side, both sides, or in the middle. A cleft palate occurs when the palate (the roof of the mouth) contains an opening into the nose. The te ...

Popular culture

Via a photo shown on a Facebook page, the mother of a child previously diagnosed with this condition recognised the symptoms and reported them to the family involved, resulting in an immediate diagnosis that medical professionals had overlooked in all earlier consultations.

References

External links

{{Medical resources , ICD10 = {{ICD10, Q, 75, 0, q, 65 , ICD9 = {{ICD9, 756.0 , ICDO = , OMIM =190440 , OMIM_mult = , MedlinePlus = , eMedicineSubj = , eMedicineTopic = , DiseasesDB = 33252 Congenital disorders of musculoskeletal system